The present invention relates to devices for treating incontinence and other similar problems in humans, and in particular to devices, and methods for their manufacture, that serve to form a seal with at least a portion of the urinary tract, to prevent the unwanted discharge of urine from the urinary tract.
Urinary incontinence is a problem faced by both women and men. The most common form of incontinence is known as stress incontinence, and incidences of this form of incontinence are significantly higher in women than in men. Many different forms of treatment are currently in use.
Although most incontinent people are not treated with indwelling catheters, some (for example, certain comatose patients) may not have alternatives other than using indwelling urinary catheters. Urinary catheters that are not indwelling or self-retaining, but can be intermittently inserted into the urinary tract for periodic (or intermittent) drainage, have also been used for fully draining the bladder. Such catheters usually are simple smooth tubes with rounded tips for ease of insertion and therefore are not self-retaining. A drain eyelet is present near the tip of the catheter to allow urine to enter the catheter. Such simple devices may be self-administered by the patient. Many incontinence problems can be helped by the use of such intermittently administered devices. However, for many incontinent female patients, unlike males who can wear external urinary catheters, during the period between drainage using intermittently administered catheters, diaper products must be used. Such diaper products are bulky, inconvenient, and may result in embarrassing situations for the patient if not attended to properly.
Another type of intermittently administered devices include urethral plugs. These plugs, including Foley catheters that are clamped off, are designed to be placed in the urethra and/or the bladder neck, and once in position, in the urethra or bladder neck, are expanded by inflation with gas (air), liquid, or the like. This inflation is typically performed by connecting a syringe, filled with air or liquid, with a valved tube built within the plug body. Before removal, the expanded portion of the plug, must be deflated. Both the inflation and deflation processes require the user to be capable of properly expanding and deflating the device, in order to properly insert it and remove it, and so as not to damage the urethra. These devices require manual deflation prior to removal from the urinary tract, such that an incapacitated (e.g., unconscious) user would risk overfilling of the bladder, causing severe kidney damage and even death.
These conventional plugs are relatively costly to manufacture, and disposable plugs, used once between voidance, are preferred in order to maintain sterility to avoid infection. Accordingly, manufacturing costs are a significant factor in commercial viability of disposable plug devices.
Traditionally, catheter manufacturing methods, such as those for making Foley catheters include processes that involve slipping a band of cured rubber over a double lumen latex rubber tubing and affixing the band on the double lumen tubing by dipping the band and the tubing in a suspension of latex to form an outer layer. The cost of manufacturing traditional Foley catheters has been influenced by the need to use a significant amount of hand labor to make the devices.
It will be appreciated that using such traditional methods to make catheters and other polymeric structures that have a variety of outer shapes and sizes with cavities (especially fluid-filled cavities) between the tubing and the outer layer adds significantly to the cost of production. Moreover, in many cases where a polymeric structure such as a catheter is to have a cavity filled with fluid, traditional manufacturing methods can not be used.
In addition to catheters, numerous devices such as gastronomy devices for transporting fluids into and out of various segments of the gastrointestinal system, for example, the stomach, also have a structure of an overcoat layer on an inner tubular structure defining a cavity therebetween. Many devices also require a self retention capability such as in the case of external feeding tubes.
Providing an automated method of manufacturing these polymeric structures and others would reduce the cost of many products incorporating such polymeric structures so that they would be more competitive in the market place and could be used for disposable products where low cost is essential.
The present invention includes polymeric structures, especially polymeric structures with encapsulated fluid filled cavities. In addition, the present invention provides methods for manufacturing the device of the present invention, that offer substantial advantages over traditional manufacturing methods.
The present invention improves on the prior art by providing a single use (used once between voidance) disposable urethral device, that requires minimal user skill for insertion and removal and is manufactured at a low cost. The device of the invention is preferably designed to work within the mammalian urinary tract, whose main structures include, but are not limited to, the meatus urinarius, urethra, bladder neck and bladder. More specifically, the device is preferably designed for use in the urinary tract of a human female, to block the flow of urine when deployed therein. The device is designed to exert a pressure in response to that of the structures of the urinary tract, such that the device can be removed from the urinary tract, and ultimately the body, by the user, manually initiating deformation of the device, or simply by voiding (urinating).
Voidance will normally dislodge the device of the invention in and from the urinary tract and out of the body. Accordingly, the device of the invention provides the user with an added degree of safety. For example, if the user were incapacitated, unconscious, or in other similar impaired conditions, voidance would occur naturally, such that the device would be forced out of the body. As a result of the invention, unlike the conventional plugs, urine would not remain in the bladder and back up in the kidneys, so as to severely damage the kidneys bladder and other structures of the urinary tract, or result in death to the user, until medical or other personnel could attend to removing these conventional plugs.
In human females, the urethra is about 4 cm in length, Gray""s Anatomy, Thirty-Eighth Edition, Pearson Professional Limited (1995), and its undilated diameter is about 6 mm (0.25 in), Tortora, Principles of Human Anatomy, Sixth Edition, Biological Sciences Textbooks, Inc. (1991). It is commonly flaccid when in its normal undilated state. While in this undilated state, the urethra commonly has a ribbon-like shape. Upon typical dilations, such as the passage of urine during voidance, the urethra takes a rounded ovular or flattened tube shape, and expands such that the cross-sectional diameter (hereafter diameter) increases from that of the urethra in the undilated state. It is this undilated diameter of the urethra that will be referenced throughout this application as the xe2x80x9cdiameterxe2x80x9d, for purposes of uniformity, as it is well known that the urethra can be dilated into many shapes (cross sectional) of varying diameter.
The device is such that it is typically of a shape with a portion thereof having a diameter greater than that of an undilated urethra, but can be deformed by urethral wall pressure such that the diameter changes at various points along the urinary tract, for insertion, deployment and removal therefrom. Use of this device allows the user complete freedom of movement without fear of urine leaking from the urinary tract as a result of body reflexes such as sneezing, coughing, laughing, straining, freeing the user from diapers tubes or the like, that are often embarrassing to the user.
The present invention also relates to methods of making polymeric structures (i.e., urethral devices) where a cavity is formed between an inner polymeric layer and an outer polymeric layer. These polymeric structures are formed as shaped structures, and in particular, the shaping is of the cavity. These shaped cavities may be fully or partially filled with fluid (liquid or gas) or not filled at all. They may also be filled with a solid piece, or combinations of solids, liquids and/or gases.
The shaping may be achieved by coating an inner piece (e.g., a polymeric tube or shaft) with single or multiple coatings of bond-preventing agent(s), in various steps. The coating of bond-preventing agent remaining on the inner piece, before the coating of a liquid polymeric overcoat layer, is herein referred to as the xe2x80x9cresidual coating.xe2x80x9d The shape of the overcoat layer results from the varying thickness of the residual coating of the bond-preventing agent.
The residual coating, that gives shape to the overcoat layer, is achieved by coating portions of an outer surface of the inner piece with a bond-preventing agent in a plurality of dipping steps by immersing the inner piece into the bond-preventing agent to a desired depth for a desired length of time and subsequently removing the inner piece from the bond-preventing agent. The desired depth and the desired length of time for each of the plurality of dipping steps is selected so that a residual coating of bond-preventing agent of a desired thickness and shape remains on portions of the inner piece following the plurality of dipping steps.
The residual coating has a specific shape as a result of the variation between the depth of any two of the multiple of dipping steps, the number of dipping steps, the length of time between any two of the multiple dipping steps, and the varying speeds of withdrawal from the tanks of bond-preventing agent and stripping agents. By appropriate coating (with bond-preventing agent) and stripping (with stripping agents), the bond-preventing agent can be sculpted to result in desired shapes, as is achievable using conventional technology such as lathes.
The sculpted residual coating can have varying thickness, curves, and angles, and therefore, a specific desired shape. By subsequently coating the residual coating of bond-preventing agent, that coats the inner piece with a polymeric bonding composition, a shaped overcoat layer is formed wherein the shape of the overcoat layer results from the varying shape of the residual coating.
As used herein, two structures of similar shapes, but having unequal ratios of dimensions in the two structures are considered to have different shapes. For example, annular cylinders with the same inside diameter and length but different outside diameters are not considered to have the same shape.
In making the polymeric structures of the present invention, with the method of the present invention, the outside dimensions (e.g., diameter) can be made with more consistency than in similar products made by traditional manufacturing methods. The methods of the present invention make possible the highly automated process of fabricating polymeric structures with shaped gel-filled, liquid-filled or air-filled cavities, especially those with a soft, outer, elastomeric layer that can conform to the contour of a surface in contact therewith.